BlaBlaCar? What do you know?

Never heard of BlaBlahCar. To get between Venice and Ljubljana, you can take either GoOpti or DRD. Both offer direct bus or van service. DRD has scheduled service and costs 25 Euros. You have to preschedule GoOpti rides but they can be cheaper than DRD for shared transfers, if you book far enough in advance.

To get between Sarajevo and Ljubljana, I'd probably fly. Adria's non-stop flights don't seem expensive to me.

Never used it but it is well know for car sharing - like Airbnb bit for car sharing.

Andrew, this is very useful information. Thank you! DRD bus line did not show up in any of my on-line research. Missed it somehow. Also, I'll rethink the Adria flight between Sarajevo and Ljubljana. It's currently 107 euros, however that's a dependable (we hope!) way to get between the two cities, offered daily... I really appreciate your help.

I have used DRD several times between Venice and Ljubljana, as recently as last May. Just note that they are not quite a conventional bus company. Don't expect to show up and just buy a ticket the day of departure (though I have been lucky and done that). You can buy tickets ahead of time on their website. In addition, I would plan to have a mobile phone to confirm with them day of travel especially if you are going from Italy to Ljubljana (from Ljubljana to Venice I would be less worried).

Many Slovenes seem to prefer GoOpti. Even though they don't offer scheduled service, they have a great reputation. If you can be flexible enough to accept a departure time you won't find out until the day before, I'd probably go with them, actually.

We tried to take them, but did not have a local phone number and an email address was unaceptable so no luck. Instead this past spring we used Adria to fly from Sarajevo to Ljubjlana, quick and easy flight. Then walked out the front door at the airport, across the road and the bus into town was there in the parking lot, 5 euros one way per person, beautiful view of the mountains including Mount Triglav. The next day caught Arriva Bus to Trieste, 2 hrs, 9 euros per person one way and 1 bathroom stop. Bought the tickets on line earlier. Bus left around 6AM. Dropped us off at the bus station in Trieste which is next door to the train station. After a few days in Trieste took the train to Venice, bought the tickets in advance. If you have extra days I recommend Trieste.

I wanted to use BlaBlaCar for one trip because it was suggested by some French friends. They seemed to feel it was an affordable, safe option for getting from place to place. I couldn't find an app in any of my American app stores so I gave up and haven't yet used it. The bus sounds like a good option.

The Slovenian alternative to Blablacar is Prevoz.org and it is about the only ride sharing service that is in any considerable use in Slovenia, outside of closed Facebook groups - hey, it's a small country. I've used Prevoz a few times on domestic routes that are poorly served by public transport and it's OK.

That said, Sarajevo to Ljubljana will be an awfully long trip by car, at least 6 hours or so. I would definitely consider flying.